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Frontispiz: Responsive Organic Fluorescent Aggregates Based on Ion-π Interactions Away from Fluorescent Conjugated Groups

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Angewandte Chemie 2024年第29期136卷

作者： Guanqun Zhu Dr. Zhiyang Liu Dr. Qi Qi Dr. Junfei Xing Prof. Quan Li Institute of Advanced Materials and School of Chemistry and Chemical Engineering Southeast University Nanjing 211189 China Materials Science Graduate Program Kent State University Kent OH 44242 USA

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Responsive Organic Fluorescent Aggregates Based on Ion-π Interactions Away from Fluorescent Conjugated Groups

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Angewandte Chemie 2024年第29期136卷

Responsive organic luminescent aggregates have a wide range of application fields, but currently there is still a lack of reasonable molecular design strategies. Introducing ion-π interactions into molecules can effectively alter their luminescent properties. However, current research typically focuses on ion localization at luminescent conjugated groups with the strong interaction forces. In this work, we introduce the flexible alkoxy chain spacers between fluorescent conjugated groups and ion-π interaction sites, and then adjust the fluorescence performance of the molecule by changing the strength of ion-π interactions. Bromine ion-based molecules with strong ion-π interactions exhibit high and stable fluorescence quantum yields in crystals and amorphous powders under the external stimuli. Hexafluorophosphate ion-based molecules with weak ion-π interactions have the high fluorescence quantum yield in crystals and very low fluorescence quantum yield in amorphous powders, showing variable fluorescence intensities under external stimuli. This demonstrates a new class of responsive organic luminescent solid-state materials.

关键词： fluorescence aggregation-induced emission solid state ion-π interactions responsive material

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Inside Cover: Cucurbituril-Mediated Supramolecular Heterodimerisation and Photoinduced [2+2] Heterocycloaddition to Generate Unexpected Rotaxanes (Angew. Chem. Int. Ed. 39/2024)

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Angewandte Chemie International Edition 2024年第39期63卷

作者： Dr. Shu Zhang Liyan Zhang Aocheng Chen Yi An Dr. Xu-Man Chen Prof. Hong Yang Prof. Quan Li Institute of Advanced Materials and School of Chemistry and Chemical Engineering Southeast University Nanjing 211189 China Materials Science Graduate Program Kent State University Kent OH-44242 USA

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Fabrication of sandwich-structured capacitor containing core@shell polystyrene@graphene oxide microspheres for switchable removal of dyes from water by dielectrophoresis force

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Separation and Purification Technology 2024年 331卷

作者： Chen, Wei-Liang Cheng, Chih-Chia Lu, Chien-Hsing Chen, Jem-Kun Department of Materials Science and Engineering National Taiwan University of Science and Technology 43 Sec. 4 Keelung Road Taipei 106 Taiwan Division of Gastroenterology and Hepatology Department of Internal Medicine Chung Shan Medical University Hospital Taichung City402 Taiwan Graduate Institute of Applied Science and Technology National Taiwan University of Science and Technology Taipei10607 Taiwan Department of Obstetrics and Gynecology Taichung Veterans General Hospital Taichung40705 Taiwan Institute of Biomedical Sciences Ph.D. Program in Translational Medicine and Rong-Hsing Research Center for Translational Medicine National Chung-Hsing University Taichung940227 Taiwan

Absorption rates for traditional adsorbents were predominately determined by the concentration gradient from bulk to absorbents and surface area. A novel sandwich-structured capacitor (SSC) containing adsorbents is designed to reduce the time consuming of absorption of pollutants by dielectrophoresis force (FDEP). Graphene oxide (GO) are coated on polystyrene microspheres (PSs) as the core/shell PS@GO adsorbents that were encapsulated within the SSC to treat the solution of dye-emulsified micells (DEM). The FDEP results the assembling of PS@GOs and DEMs under polarization and enhance the adsorption rate ca. 1 ∼ 2 times with polarization at 3 V and 200 kHz. Additionally, most adsorbents are recycled with secondary pollution. Only two-fifth pure water volume of the wastewater through the SSC could achieve the recycling of the adsorbents at 900 kHz. The high complex permittivity of GO coating at high frequency allows ultrafast alternative spinning of the induced dipoles in the PS@GOs facilitates desorption and hinders the re-adsorption of the DEM during the recycling of PS@GOs. The PS@GOs was reused ca. 10 times at 20 mL min−1 of flow rate through the SSC without damages between 200 and 900 kHz. The designed SSC containing PS@GOs accomplishes either reusing of adsorbents or concentrating of dyes with low secondary pollution in practice through frequency manipulation. © 2023 Elsevier B.V.

关键词： Graphene

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Third-order optical properties of Ag nanocubes and Ag@Au hollow nanostructures investigated by femtosecond Z-Scan measurements

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Optik 2025年

作者： Claudevan A. Sousa Antonio F.A.A. Melo Nefe J.B. Silva Tânia Patrícia Silva e Silva Bartolomeu C. Viana Francisco Eroni P. Santos Hans Garcia Department of Physics UFPI - Universidade Federal do Piauí 64049-550 Teresina PI Brazil Materials Engineering Graduate Program Federal Institute of Education Science and Technology of Piauí Central Campus Teresina 64000-040 PI Brazil Interdisciplinary Laboratory for Advanced Materials BioMatLab group Materials Science & Engineering Graduate Program UFPI - Universidade Federal do Piauí 64049-550 Teresina PI Brazil

We present a comprehensive study on the third-order nonlinear optical properties of silver nanocubes (Ag-NCs) and Ag@Au hollow bimetallic nanostructures in aqueous dispersions. The Ag@Au bimetallic nanostructures were synthesized by galvanic replacement of Ag-NCs with gold, generating nanoboxes with surface plasmon resonance (SPR) tunability. Using the femtosecond Z-scan technique (1040 nm, 357 fs) across laser intensities from 99.7 to 279 GW/cm², we identified negative nonlinear refraction in both Ag-NCs and Ag@Au nanoboxes, attributed to hot electron generation. Saturable absorption (SA) was observed only in Ag@Au nanoboxes, distinguishing their potential for nonlinear photonic applications. These findings highlight the impact of morphology and composition on nonlinear refraction and absorption, positioning Ag@Au hollow nanostructures as promising candidates for active media in advanced photonic devices.

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Magnetic and Electric Behavior of Spike- and Petal-Like Nanoscaled Cu:Zno Superstructures Diluted Magnetic Semiconductors

SSRN

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SSRN 2022年

作者： Gunnewiek, Rodolfo Foster Klein Perdomo, Claudia P.F. Almeida, Diógenes F. Cancellieri, Igor C. Garcia, Leonardo A. Cardoso, André L.F. Federal University of São Carlos Graduate Program in Materials Science and Engineering Rod. Washington Luiz km 235 SP São Carlos13565-905 Brazil Federal University of Alfenas Graduate Program in Materials Science and Engineering Rod. José Aurélio Vilela BR 267 Km 533 11999 MG Poços de Caldas37715-400 Brazil Federal University of Alfenas Institute of Science and Technology Rod. José Aurélio Vilela BR 267 Km 533 11999 MG Poços de Caldas37715-400 Brazil

Room temperature ferromagnetism (RTFM) is the main condition for searching for materials to be applied in spintronics. Beyond the candidates, the diluted magnetic semiconductors (DMS) are potential materials for such application. The introduction of a foreign transition metal ion in the semiconductor lattice may lead to the RTFM, where the intrinsic ferromagnetism developed by a nonmagnetic ion is preferable for spintronics application. In this work, single-phase Cu-substituted zinc oxide was synthesized by a fast polymeric precursor method, providing nanocrystallites from 4 to 11 nm. Copper hindered grain growth, even for high Cu concentrations. The crystallites assembled to superstructures with petal and spike-like morphologies, following an unconventional crystallization. The texturization observed during the crystallization led to the development of unexpected weak RTFM. The number of oxygen vacancies is too small to promote the RTFM since few atoms of copper find attached to the vacancies. Probably the RTFM arises from overlapped spin-split bound magnetic polarons (BMP) due to the interaction of the hybridized O 2p and localized unoccupied twofold t2 subband of Cu 3d states. Although the sintering of pure and Cu-doped ZnO particles was equivalent, the electrical properties diverged. The copper insertion enhanced the resistivity and the non-linearity coefficient reached values higher than the unity. This is maybe due to the presence of copper at the grain boundaries forming a Schottky barrier. Neither the non-ohmic electrical behavior nor the RTFM from nanostructured superstructures was ever reported before. © 2022, The Authors. All rights reserved.

关键词： II-VI semiconductors

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Reduction of interface defects in gate-recessed GaN HEMTs by neutral beam etching

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materials Today Advances 2024年 23卷

作者： Yu, Chia Hao Chiang, Wei Hsiang Chen, Yi-Ho Samukawa, Seiji Wuu, Dong Sing Chung, Chin-Han Hsiao, Ching-Lien Horng, Ray Hua Institute of Electronics National Yang Ming Chiao Tung University Department of Materials Science and Engineering National Chung Hsing University Graduate Degree Program of College of Electrical and Computer Engineering National Yang Ming Chiao Tung University Institute of Comunications Engineering National Yang Ming Chiao Tung University Department of Applied Materials and Optoelectronic Engineering National Chi Nan University International College of Semiconductor Technology National Yang Ming Chiao Tung University Thin Film Physics Division Department of Physics Chemistry and Biology (IFM) Linköping University

This study investigates and compares the impact of different etching techniques on the fabrication of GaN high electron mobility transistors (HEMTs) between the inductively coupled plasma reactive ion etching (ICP-RIE) and the neutral beam etching (NBE) for the gate recess. By conducting direct current analysis, it was found that devices manufactured using the NBE exhibited superior electrical performance as compared with those produced using the ICP-RIE. These enhanced electrical characteristics include a transconductance of up to 100.4 mS/mm, a threshold voltage (V_th) of −2.3 V, an on/off current ratio of 1.1 × 10⁹, a subthreshold swing (S.S.) of 99.63 mV/dec, and a remarkably low gate leakage current. Additionally, we noted varying degrees of hysteresis in the I–V characteristics were related to process disparities possibly leading to interface defects. Multi-frequency capacitance-voltage (C–V) measurements were used to identify the interface defects at the oxide/AlGaN interface of the gate. The results revealed that devices fabricated using the NBE exhibited a lower interface defect density as compared with those fabricated using the ICP-RIE, thereby elucidating the reduced hysteresis observed in the I–V characteristics. These findings indicated the significant advantages of the NBE process in the fabrication of GaN HEMTs. © 2024 The Authors

关键词： GaN HEMTs Gate recess Interface defects Multi-frequency C–V Neutral beam etching

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Exotic Magnetism in Oxidized Copper Chloride

SSRN

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SSRN 2023年

作者： Pimentel, Dyvison Pedreira Campinas São Paulo13083-859 Brazil Federal Institute of Maranhão IFMA-PPGEM Avenida Getúlio Vargas 4 MA São LuísCEP 65030-005 Brazil PPGCM-Materials Science and Engineering Graduate Program UFPI-Federal University of Piaui PI Teresina64049-550 Brazil

In this work magnetization measurements in oxidized CuCl are presented. Two magnetic transitions are clearly observed, one around 6.4 K and the other around 18 K. Such magnetic transitions are closely related to Clinoatacamite Cu2Cl(OH)3. Interestingly, another transition is observed at 16 K which is also very difficult to know its origin. The apparent "diamagnetism" observed in the ZFC measurements is due to the exchange bias effect, leading to the conclusion that our CuCl samples are in a highly frustrated state due to the presence of clinoatacamite. X-ray diffractograms at different time intervals of exposure to air of the virgin CuCl sample to determine the appearance of new phases in the material composition were carried out. The results obtained show us that an exposure prolonged exposure to air, air humidity and oxygen actually leads to the gradual transformation of CuCl to Clinoatacamite. © 2023, The Authors. All rights reserved.

关键词： Copper compounds

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Magnetically tuned continuous transition from weak to strong coupling in terahertz magnon polaritons

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Physical Review Research 2023年第1期5卷 L012039-L012039页

作者： Andrey Baydin Kenji Hayashida Takuma Makihara Fuyang Tay Xiaoxuan Ma Wei Ren Guohong Ma G. Timothy Noe, II Ikufumi Katayama Jun Takeda Hiroyuki Nojiri Shixun Cao Motoaki Bamba Junichiro Kono Department of Electrical and Computer Engineering Rice University Houston Texas 77005 USA Smalley-Curl Institute Rice University Houston Texas 77005 USA Division of Applied Physics Graduate School of Engineering Hokkaido University Sapporo Hokkaido 060-8628 Japan Department of Physics and Astronomy Rice University Houston Texas 77005 USA Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston Texas 77005 USA Department of Physics International Center of Quantum and Molecular Structures and Materials Genome Institute Shanghai University 200444 Shanghai China Department of Physics Graduate School of Engineering Science Yokohama National University Yokohama 240-8501 Japan Institute for Materials Research Tohoku University Sendai 980-8577 Japan The Hakubi Center for Advanced Research Kyoto University Kyoto 606-8502 Japan Department of Physics I Kyoto University Kyoto 606-8502 Japan PRESTO Japan Science and Technology Agency Kawaguchi 332-0012 Japan Department of Materials Science and NanoEngineering Rice University Houston Texas 77005 USA

Depending on the relative rates of coupling and dissipation, a light-matter coupled system is either in the weak- or strong-coupling regime. Here, we present a unique system where the coupling rate continuously increases with an externally applied magnetic field while the dissipation rate remains constant, allowing us to monitor a weak-to-strong coupling transition as a function of magnetic field. We observed a Rabi splitting of a terahertz magnon mode in yttrium orthoferrite above a threshold magnetic field of ∼14 T. Based on a microscopic theoretical model, we show that with increasing magnetic field the magnons transition into magnon polaritons through an exceptional point, which will open up new opportunities for in situ control of non-Hermitian systems.

关键词： Antiferromagnetism High magnetic fields Magneto-optics Magnons Polaritons Non-Hermitean systems Terahertz time-domain spectroscopy Transfer matrix method

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Effect of Surface Activation on the Corrosion Resistance of a MAO/Ni-P Composite Coating on LZ91 Magnesium Alloy

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Journal of the Taiwan Institute of Chemical Engineers 2023年第1期147卷

作者： Chen, Chi-An Lee, Jeou-Long Jian, Shun-Yi Lee, Chia-Yu Ger, Ming-Der Combination Medical Device Technology Division Medical Devices R&D Service Department Metal Industries Research & Development Centre Kaohsiung802 Taiwan Department of Chemical and Materials Engineering Lung Hwa University of Science and Technology Taoyuan330 Taiwan Department of Material Engineering Ming Chi University of Technology New Taipei City Taiwan Center for Plasma and Thin Film Technologies Ming Chi University of Technology New Taipei Taiwan Graduate School of Defense Science Chung Cheng Institute of Technology National Defense University Taoyuan Taiwan Department of Chemical & Materials Engineering Chung Cheng Institute of Technology National Defense University Taoyuan Taiwan System Engineering and Technology Program National Chiao Tung University Hsin-Chu Taiwan

Background: LZ91 Magnesium alloy with a dual-phase structure has improved mechanical properties and a low density of about 1.48 g/cm3 but their limited resistance to corrosion limits their application. Therefore, it is a great challenge to increase the stability of LZ91 alloys under corrosive factors and environments. Methods: This study uses micro-arc oxidation (MAO) and an electroless nickel-phosphorus (Ni-P) plated composite film to increase the corrosion resistance of LZ91 magnesium alloy. Before electroless Ni-P plating, the MAO layers are activated by palladium catalysts at different pH values to produce composite coatings. SEM, EDS and Image J are used to determine the surface properties and elemental composition of the samples. The corrosion resistance is measured using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. Findings: The results show that the MAO coating is activated by an acid catalyst and the surface is obviously corroded. The electroless Ni-P plating grows into the MAO coating and the substrate corrodes. Therefore, corrosive medium (chloride ion) easily enter to the substrate and pitting corrosion occurred. On the contrary, activation by a neutral catalyst (pH=7) maintains the original structure of the MAO coating and provides a good bonding interface for the Ni-P coating. Form the potentiodynamic analysis can be finds that the corrosion potential for the neutral catalyst treated sample is -0.35V and the corrosion current density value is 1.77×10−6 A/cm2, so the corrosion characteristic become better than the acid catalyst treated samples. In terms of the long-term resistance after 48 h, EIS analysis shows that the resistance value remains at about 7.6×104 Ω•cm2. A composite coating that is compact and with excellent resistance to corrosion resistance is produced, which provides better protection for LZ91 magnesium alloys. © 2023 Taiwan Institute of Chemical Engineers

关键词： Corrosion resistance

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